On the covered Rinnai tankless water heater, FF means a maintenance indicator: a placeholder in the diagnostic code history showing that a service provider performed maintenance or service. It is not a fault. First, nothing needs to be done for an FF entry.
Differential
Likely causes of “Rinnai tankless water heater code FF”, and how to tell them apart
- 1
A service entry in the code history
What separates it FF appears when the history is read
How to confirm Nothing needs to be done
- 2
A technician keyed it after a visit
What separates it The history shows FF after service
How to confirm It records that maintenance happened
- 3
Confusion with a fault
What separates it Hot water is working normally
How to confirm Do not call for service because of FF alone
- 4
A real fault listed beside it
What separates it A different code is shown now
How to confirm Read that code instead
- 5
An old entry
What separates it FF stays in history
How to confirm It does not clear hot water problems
Before you touch a setting
Record this first — changing settings destroys the evidence
- Whether hot water works
- What other codes are in the history
- When the unit was last serviced
- The model number on the rating plate
Try in this order
0 of 8 completedWhat to do first
ReversibleNothing needs to be done for an FF entry.
Correct only the documented fault domain
ReversibleRinnai says a technician enters this code after service by pressing Up, Down and On/Off simultaneously. It appears in the code history, not as a fault.
Check hot water
ReversibleIf it works, FF is not a fault.
Read the code history
ReversibleOn the controller.
Look for other codes
ReversibleThose are the faults.
Note the last service date
ReversibleFF records one.
Do not reset for FF
ReversibleNothing to reset.
Call a technician
ReversibleIf hot water fails.
Model-specific
What is true of this model and not of its siblings
- A placeholder, not an alarm
- Rinnai describes FF as a placeholder that a service provider enters after performing maintenance, by pressing Up, Down and On/Off together. It shows that someone serviced the unit and when, so it is useful to a technician reading the history, and meaningless as a warning.
- Reading the history
- The code history lists recent codes in order. If you see FF between real fault codes, read the codes around it. A history full of the same fault code, such as an ignition or a flame problem, points to what needs repair.
- Maintenance that matters
- A tankless heater benefits from a yearly flush to remove scale, a check of the inlet water filter and a look at the vent. The FF entry records that this was done; if it was a long time ago, schedule it again.
Stop boundary
When this stops being a self-service repair
- !If a real fault code shows beside FF, follow that code
- !Contact a technician for any hot water problem
- !Keep service records
Evidence ledger
Sources behind this answer
Exact questions
Common questions
What does FF mean on a Rinnai tankless water heater?+
A maintenance indicator: a placeholder in the diagnostic code history showing that a service provider performed maintenance or service. It is not a fault.
Who enters it?+
A technician, after service.
Do I need to act?+
Not for FF itself.
Where does it appear?+
In the diagnostic code history.